1. Field of the Invention
This invention relates to a portable machine tool for preparing open ends of pipe fittings for welding.
2. Description of Related Art
Pipe end preparation tools used to machine open ends of pipes or pipe fittings for welding are disclosed, for example, in U.S. Pat. Nos. 3,103,140, 3,992,123, 4,126,065 and 4,343,207. As can be observed, typical end preparation tools are designed to be portable for use at or near a welding site and include various arrangements for locating pipe or pipe fitting to be machined relative to a rotary cutting head that carries apropriate shaping tool bits that are fed into engagement with the pipe end to be prepared in a precise manner.
Prior art arrangements of pipe and pipe fitting end preparation tools have been found to be lacking in providing a suitable arrangement for universally clamping a pipe fitting in a manner whereby various end surfaces of the pipe fitting can be precisely machined in preparation for welding. Various mandrel arrangements have been utilized as well as clamping systems to locate the pipe or pipe fitting relative to the cutting head of the end preparation tool, but typical known arrangements require the fitting to be disengaged by the mandrel or clamping means each time a different surface of the fitting is to be machined by the end preparation tool.
It is generally known that high volume production systems utilize various arrangements of jigs and fixtures to locate odd shaped pieces relative to a machine tool, but such systems do not generally include arrangements for universally engaging various sizes and shapes of fittings and securing them in place during machining operations on various surfaces of the workpiece without the need for unclamping and relocating the workpiece each time a different end surface of same is to be machined.